Beware, Not Everyone Lies the Same Way! Investigating the Effects of Interviewees’ Profiles and Lie Content on Verbal Cues

Research shows that lying is a common behaviour, and that verbal cues can be effective for lie detection. However, deception detection is not straightforward as there are several factors at play, such as interpersonal differences and the content of the lie. Consequently, the effectiveness of available cues for deception detection can vary significantly. In a pre-registered study involving 80 participants (a priori sample size analyses were conducted), we instructed participants to either tell the truth or lie about an autobiographical event and an opinion. The participants also completed questionnaires on personality traits and cognitive tasks, resulting in two participant clusters. Surprisingly, when analysing verbal behaviour, truthfulness, cluster memberships, and their interactions were not found to be significant. Only lie content affected verbal cues. Additional, non-pre-registered analyses revealed that liars displayed more micro-expressions than truth tellers, but only when describing their memories and when focusing on the latency time between the investigator’s question and the interviewee’s answer. The results were interpreted in terms of the experimental design, which encouraged only short answers from the interviewees, leaving limited room for verbal content to be effective.